The performance of a quantum information processor depends on the precise control of phases introduced into the system during quantum gate operations. As the number of operations increases with the complexity of a computation, the phases of gates at different locations and different times must be controlled, which can be challenging for optically-driven operations. We circumvent this issue by demonstrating an entangling gate between two trapped atomic ions that is insensitive to the optical phases of the driving fields, while using a common master reference clock for all coherent qubit operations. Such techniques may be crucial for scaling to large quantum information processors in many physical platforms.
@article{arxiv.1405.5207,
title = {Quantum Gates with Phase Stability over Space and Time},
author = {I. V. Inlek and G. Vittorini and D. Hucul and C. Crocker and C. Monroe},
journal= {arXiv preprint arXiv:1405.5207},
year = {2014}
}